Back in the “old days”, people used to take a look at a three-letter code on CD packaging that indicated the domain used for the Recording, Mastering, and Distribution media. Usually, you saw things like “DDD” (meaning “Digital, Digital, Digital”) or “ADD” (for an Analogue recording that was mastered and distributed in the Digital domain).

Nowadays, there’s plenty of discussion about “high-resolution” audio – but one of things that nobody has seemed to agree on is exactly what is “high” and what is “normal” resolution (although I, personally, would also include George Massenburg’s call for a “Vile-Resolution” classification as well).

Well, finally, important people have gotten together to agree on how high is enough to be called “high”  – and how to tell consumers about it. The details can be found here: Link.

Some details from that page are below

The descriptors for the Master Quality Recording categories are as follows:

MQ-P
From a PCM master source 48 kHz/20 bit or higher; (typically 96/24 or 192/24 content)

MQ-A
From an analog master source

MQ-C
From a CD master source (44.1 kHz/16 bit content)

MQ-D
From a DSD/DSF master source (typically 2.8 or 5.6 MHz content)